1. Field of the Invention
The present invention relates to an information processing apparatus for determining a height of a toner image formed on an image bearing member, an information processing method, and an image forming apparatus.
2. Description of the Related Art
A color of an image formed by an electro-photographic image forming apparatus, e.g., a copying machine, a laser printer, and a fax machine, varies according to changes of various kinds of physical parameters even when settings of the apparatus in image formation are the same. More specifically, the change in the physical parameters in a developing/transferring process tends to be a factor of a color variation.
This is because, the physical parameters, e.g., a latent image potential, a toner replenishment amount, and a transfer efficiency varies according to an environmental fluctuation of, for example, a temperature and humidity, and thus toner adhesion amounts to be adhered to a photosensitive drum and a transfer belt vary.
Therefore, stabilization of the developing/transferring process is required. The stabilization is realized in such a manner that the toner adhesion amounts on the photosensitive drum or the transfer belt is measured and, and based on the measurement result, an amount of exposure, a developing voltage, and a transfer current are controlled.
Generally, these controls are executed when the environmental fluctuation occurs, e.g., after an exchange of a toner cartridge, after printing of a predetermined number of sheets, and after power of a body of the image forming apparatus is turned on. When measuring the toner adhesion amounts, a plurality of toner images (i.e., toner patches) having various densities, i.e., from a low density to a high density, are formed on the photosensitive drum and the transfer belt. Subsequently, the toner adhesion amount measurement device measures the toner adhesion amounts of the toner images and performs various controls under proper image forming conditions based on the measurement result.
A typical toner adhesion amount measurement device emits light from an LED light source and detects a light quantity of reflected light reflected on the toner image, thereby measuring the toner adhesion amount. According to another method, a physical form of the toner image (i.e., a thickness of the toner image, namely, a toner height) is measured by a profilometer including a laser displacement meter.
Japanese Patent Application Laid-open No. 04-156479 discusses a measurement method in which a toner image formed on each of a photosensitive drum and a transfer belt is irradiated with a laser beam and reflected light therefrom is captured by a line sensor including light-sensitive elements arranged in line, thereby measuring the toner height.
The toner height of the toner image formed on a image bearing member such as the photosensitive drum and the transfer belt is extremely low, i.e., from a several micrometers to about ten micrometers, in the electro-photographic image forming apparatus. Therefore, in order to measure the toner height by using the profilometer, detection of a minute step between a surface of the image bearing member and a surface of the toner image, is required. However, in the conventional method, e.g., a method discussed in Japanese Patent Application Laid-open No. 04-156479, the toner height could not be detected with high accuracy.